Locking device



Nov. 13, 1928.

W. F. ZIMMERMANN LOCKING DEVICE Filed Oct. 1926 INVENTOR. Wziiz'mmli'lmmermo'zzn BY I a? /-//S ATT NEY Patented Nov. 13, T928.

tlhl-ll li STATES wzLLrz-na FRANK ZIMMER-MANN, or wnvnnnv, NEW Yonn,ASSIGNOB T0 INGERSOLL-.,.

PATENT OFFICE.

RAH}? GGMPAHY, OF JEPJSEY CITY, NEW JERSEY, A OGREORATION OF NEW JERSEY.

LOCKING DEVICE.

This invention relates to pneumatic tools, but more particularly to alocking device for pneumatic sand ,raninier's and the like in which theparts comprising the casing are secured together by means of screwthreads.

The object of the invention is to insure a tight connection between thecasing parts of sand rammers and similar tools.

Other objects will appear hereinafter.

The invention is shown in one of its preferred forms in the accompanyingdrawings, in which Figure 1 is an elevation, partly in section, of asand rammer equipped with a locking device constructed in accordancewith the practice of the invention,

Figure 2 is a side elevation of the upper or rearward portion of thesand rammer and Figure 3 is a transverse view taken through Figure 1 onthe line 33 looking in the direction of the arrows.

Referring to the drawings, the invention is shown applied to a pneumaticsand rammer having a cylinder A provided with a reciprocatory hammerpiston B. A bushing C screwed into the front end of the cylinder A formsa closure therefor and acts as a guide for a shank D of the piston B onwhich is fastened a butt or pein E as a working implement, said shank Dbeing an extended and smaller portion of the piston B. Passages F and Gare formed in the cylinder A to convey pressure fluidto the front andrear ends respectively for actuating the piston B. The passages'F and Gin this instance lead from the rearward end of the cylinder A and areintended to be controlled by a suitable distributing valve (not shown)but which may be encased by a valve chest H situated at the rearward endof the cylinder A. A free ex haust port J in the cylinder A is in thisinstance controlled only by the piston B.

In the present instance the rearward end of the cylinder A is screwthreaded as at K' to cooperate witha correspondingly threaded portion Lof a hoodzO. The hood 0 is provided with a recess P to'accommodate thevalve chest H and serves to hold said valve chest firmly in assembledposition against the end of the cylinder A. a

Pressure fluid is in this instance conveyed to the valve chest H througha pipe or conduit Q which may also serve as a handle or stem whereby thetool may be guided and hel d to the worln In accordance with thisinvention means are provided for preventing accidental unscrewing of thehood O from the cylinder A as well as to automatically tighten theconnection between the hood and the cylinder in case the cooperatingthreads of these elements be come slightly worn due to the vibration ofthe tool during its operation. To this end teeth R are cut radially inthe forward end S of the hood O and these teeth are prefe=rably givenboth a longitudinal and radial back taper to insure constant engagementof the teeth R with similar teeth T carried by a key U. The key U inthis instance is of arcuate form and its inner surface V preferablyconforms substantially to the outer surface of the cylinder A whereon itis slidably mounted.

In order that the key U may be at all times pressed firmly against theteeth R of the hood 0, a spiral tension spring W located wholly at oneside of the cylinder is secured at one end to the key U by means of apin X and anchored at its other end to apin Y secured fixedly to thecylinder A is adapted to exert a constant pull on the key tendingtorotate the hood 0 in the direction in which the hood is screwed on thecylinder.

T0 at all times protect the spring W against injury as well as toprovide an additional means for preventing the key U from beingaccidentally disengaged from the hood 0, a cylindrical split sleeve Z isarranged around the rearward end of the cylinder A and is preferably ofa length to encircle slidably the forward or serrated portion of thehood 0. This sleeve Z in this instance also serves as a muflier for thepressure fluid issuing from the free exhaust port J and is provided witha plurality of apertures b for the escape of pressure fluid from theinterior of the sleeve to the atmosphere In practice, whenever it isdesired to unscrew the hood 0 from the cylinder A, the sleeve Z may beslightly spread and moved forwardly on the cylinder A in advance of thekey U. The key U may then be disengaged from the hood O and the hoodunscrewed from thecylinder in the usual manner. After the hood has againbeen screwed on the cylinder, the key U may be moved around the cylinderuntil a considerable tension is set up in the spring W. The teeth of thekey may then be placed in engagement with the teeth on the hood and,owing to the back taper of the contacting surfaces of the cooperatingteeth, the key U will be held against disengagement from the hood 0.

The above described device forms a simple and effective means formaintaining a tight connection between the hood and the cylin der. Owingto the constant tension exerted by the spring W, the cooperating threadsof these parts will be subjected to a minimum amount of wear.

I claim:

In a pneumatic tool, the combination of a cylinder, a hood screwed onthe cylinder,

the hood, and a spring anchored to the cylin-- der and to the keyexerting a. constant pull tending to tighten the connection betweentheir hood and the cylinder.

In testimony whereof I have signed this specification.

WILLIAM FRANK ZIMMERMANN.

